[(5,6-Dicarboxy-3-pyridyl)methyl]ammonium halides are useful as intermediates in the preparation of herbicidal 5-(alkoxymethyl)-2-(2-imidazolin-2-yl)nicotinic acids, esters and salts. A process for converting 5-methyl-2,3-pyridinedicarboxylic acid derivatives into [(5,6-dicarboxy-3-pyridyl)methyl]-ammonium halides is described in U.S. Ser. No. 5,378,843. Although the process of that patent is useful, there is ongoing research to discover new processes for preparing [(5,6-dicarboxy-3-pyridyl)methyl]ammonium halides.
It is, therefore, an object of the present invention to provide an effective and efficient process for the preparation of [(5,6-dicarboxy-3-pyridyl)methyl]ammonium halides.